This application relates to a lost core for forming cooling channels in a gas turbine engine component airfoil.
Gas turbine engines are known and, typically, include a fan delivering air into a bypass duct as propulsion air and into a core engine, where it reaches a compressor. The air is compressed and delivered into a combustion section. The air is mixed with fuel and ignited and products of this combustion pass downstream over turbine rotors driving them to rotate.
The products of combustion are extremely hot and, thus, there are challenges to airfoil durability in the turbine section. As an example, the turbine rotors carrying rotating blades that have airfoils. In addition, there are static vanes having airfoils intermediate stages of the rotating blades. It is known to provide cooling air to internal channels within these airfoils.
An airfoil typically extends from a leading edge to a trailing edge. Cooling channels are provided at the trailing and leading edges.
Internal cooling channels may be formed by a lost core mold techniques. In such technique, a lost core is made which essentially follows the contours of the desired cooling channels. That lost core is placed within a mold and molten metal is molded around the lost core. The lost core is then leached out leaving a hollow cavity within the solidified metal airfoil.
In one application of lost cores, there is a first leg forming a cooling channel adjacent to at least one of the leading and trailing edges. Crossover holes connect this channel to a channel spaced from the leading or trailing edge. These crossover holes are formed by crossover members on the core. To prevent breakage to the core during the molding process and leading up to the molding process, the extreme end crossover members are formed to be of greater cross-sectional area. Such crossover members are called frames.
However, the frames have not always provided sufficient strength and prevention of damage.